The invention relates to a blade mounting for the cutting tool of a fixed block or blade-disk chipper of a wood-chipping machine.
In the production of chips having chip thicknesses of over 0.7 mm, as are required for certain special boards, high cutting and feed forces are generated which, in the unavoidable chipping of end-grained wood sections, exert correspondingly high displacement forces on the cutting edges of full-cut blades. This is particularly true of disk chippers, whose cutting speed in the inner area of the disk is only around 35% of the cutting speed of the outer area. Most disk chippers operate at a blade setting angle, advantageous to the chip surface, of 35.degree.. At a setting angle of 35.degree., the displacement forces have an even more adverse effect than in the case of setting angles of around 45.degree., which are also employed.
If the chipper blades are retracted during chipping, this can sometimes result in damage to the surface of the cutting tool and the blade clamping elements. In such cases, it is often not sufficient to join the chipper blade and blade holder with more than two connecting screws, particularly where the blade length exceeds 400 mm. High-capacity disk chippers, equipped with blade mountings according to German Offenlegungsschrift 39 33 880, require chipper blades of such a length where the disk diameters measure 3,000 mm or more.
U.S. Pat. No. 3,542,302 discloses a blade mounting wherein the chipper blades and the blade holders are adjusted, following regrinding, by means of adjusting screws which are inserted into the bottom edges of these elements. Assuming a universally common regrinding width of 40 mm and a 1 mm regrind in each case, 40 readjustments would need to be made. Where the chipper blades are only 4 mm thick, such an arrangement does not work.
German Offenlegungsschrift 35 06 252 discloses a blade mounting having angle brackets, the short leg of which bears with its inner surface against the bottom edge of the blade. The screw connection of the angle bracket is effected by means of adjustably disposed clamping screws, which open out into retaining bolts guided through holes in the chipper blade. In addition, a plurality of permanent magnets are housed in the blade holder. The clamping forces which can be obtained with this blade mounting are no greater than with a conventional screw connection.